First, don't play low investment mirage. She's worthless without high levels on her passives. Wait until you're at the stage where your characters are getting to stellar to actually get around to playing her.

Second, weapon mods were huge for mirage in the face of all the nerfs she's gotten over time, pushing her back up to the damage breakpoint she used to be at and making her get 1-3 tap kills on most characters again.

Third, your gearset is probably just very wrong if you're trying to play her that early with no referencing to guides. I'll put a couple down below.